Carburetor



E y n April?, 1936.I` sG. R. ERKCSON GARBURETOR Filed Jn. l2, 1932 IINVENTCR ATTORNEY Patented pr. 7, 1936 UNITED vs'm'r'lzs CARBURETOR George R. Ericson, Maplewood, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application January 12, 1932, Serial No. 586,185

6 Claims.

This invention relates to carburetors for internal combustion engines, and more particularly to anti-stalling devices for automotive engines.

In previous carburetors of this type, certain difficulties have been experienced, because stalling frequently occurred, and smoke and carbon monoxide gases were produced in substantial quantities when the automobile was coasting downhill with the throttle closed, or when the engine was suddenly decelerated by closing the throttle. The imperfect combustion which results in the frequent stalling and the production of carbon monoxide gas under'these conditions is due to several reasons, the two most important of which are as follows:

The low pressure in the intake manifold under these conditions lowers the boilingvpoint of such gasoline as may be in the manifold and causes the vaporization of this fuel, thereby giving an unduly rich mixture.

The other reason is that the combustion takes place undervery low compression, frequently at or below atmospheric pressure. The combustion of the charge under these conditions is always oxide gas could be eliminated and also a substantial amount of both oil and fuel could be saved by cutting olf the fuel supply altogether whenever the engine is being operated with the throttle closed and-at higher than normal idling speed.

It is an object of this invention to produce a device capable of automatically cutting off or at least substantially reducing the supply of fuel to the engine whenever the engine is running faster than normal idling speed, with the throttle completely closed.

It is a further object of this invention to produce a device which will be capable of eliminating the production of carbon monoxide gas Whenever the engine is operating with closed throttle and at higher than normal idling speed.

Another object of my invention is to produce a device for preventing the delivery of too rich a mixture to the engine when the engine is being rapidly decelerated.

Other objects will appear' from the following description and accompanying claims.

Referring to the drawing,

Figure l is a sectional elevation of a carburetor embodying my invention.

, Figure 2 is 'an inverted plan View on line 2-'2 of the device shown in Figure l.

Figure 3 is a fragmentary view showing a slight modification.

The reference numeral I indicates the main body member of a carburetor of the downdraft' type which is attached by means of a flange 2 to the manifold of an internal combustion engine, the manifold end being indicated by the reference numeral 3. The carburetor may be of the plain tube type and is provided with a` mixing conduit generally indicated by the reference numeral 4, and one or more venturis 5. The fuel is delivered to the smallest of the venturis by the nozzle 6, and is supplied to the nozzle from a bowl-1 which is of conventional construction. The fuel is maintained at a constant level A-A in the bowl by the usual iioat valve (not shown).

v The choke valve 8 and operating lever 9 therefor is provided, and a-throttle valve I Il is provided for controlling the supply of fuel and air to the engine. An idle tube I2 is formed in the main body of the carburetor and provided with a discharge port I3 adjacent the edge of the throttle I Il. This port, as will be readily under-` stood, is calibrated to suit the requirements of the engine and may be either a single slot or it may be two openings, one on each side of the edge ofthe throttle valve Ill when the throttle is in closed position. The tube I2 extends to a point above the fuel level A--A in the bowl, so that fuel will not be discharged by gravity, and a small air bleed IN is provided for the upper end of the idle tube to prevent any siphoning action. The air bleed and idling adjustment is controlled by the manually operated screw I5.

In a carburetor of the downdraft type, the fuel is supplied to the upper end of the idle tube from an upwardly extending conduit receiving fuel from the float bowl and connected to the main metering jet which supplies fuel to the nozzle 6. zThese parts, however, are of conventional construction and need not be further described.

In the lower end of the main body member of the carburetor, I provide a cylinder I6 terminating in a Valve seat Il and a bore I8 which extends into a chamber I9 at the lower end of the idle tube I2. The lower end of the cylinder I6 is closed by a plug 2|, and. the lower end of the cylinder just above the plug is connected to the mixing conduit 4 by a port 22. This connection is made below the throttle valve and on the suction side thereof. The piston 23 is slidably fitted in the cylinder IB and is provided with a valve 24. The piston is normally held in upward position with the valve closed by means of a spring so that a substantial amount of suction will be required to overcome the tension of the spring and open the valve 24 by a downward movement of the piston 23.

The normal idling suction in the intake manifold of the engine is approximately 17 inches of mercury, and the spring 25 must be strong enough to hold the valve 25 in closed position against 'that degree of suction, otherwise, the engine would not idle. 'I'he diameter of the piston 23 and the strength of the spring 25 are accordingly correlated with the diameter of the valve 24, so that a suction of about 19 inches of mercury on the head of the piston 23 will cause the valve to open. It will be noted that the valve 24 is exposed to suction as well as the head of the piston, so that when the valve is in closed position, it will take more suction to open the valve than it will to hold it open. 'I'his is for the reason that the port 26 permits the admission of air under substantially atmospheric pressure, and when the valve 24 is open, this pressure is applied to the end of said valve.

From the above description, it will be understood that I have provided a valve which is operable by suction to admit air to the idle port whenever' the normal idling suction is exceeded, and which will cut oif the admission of air to said idle port whenever the suction drops substantially below normal idling suction. The valve, however, will not have a uttering action, because it requires less pressure to hold it open than it does to open it. Y

In operation, the valve 24 does not open at all except when the suction is greater than the normal idling suction of the carburetor, and the normal operation of the carburetor is not interfered with in any way, but when the normal idling suction is exceeded by the engine running faster than the normal idling speed and with the throttle in fullyr closed position, the valve 24 is open and air from port 26 enters the chamber I 9, thereby breaking the suction on the idle tube and causing a reduction in the.. supply of gasoline. For ordinary purposes, this reduction will be so substantial as to amount to a complete cutting off of the gasoline supply, so that the mixture supplied to the intake manifold of the engine will be so lean that the engine can not continue `to operate under its own power until its speed has been reduced to normal idling speed or below. When the engine has fallen back to its normal idling speed and the suction in the intake manifold 3 has dropped to a corresponding extent, the valve 24 is closed by spring 25, and the normal idling mixture is again supplied to the engine. From this it will be seen that the engine is completely deprived of a firing mixture at such times as it is operating at higher than the normal idling speed with the throttle in fully closed position.

It willbe understood that instead of controlling the fuel discharged from the idling conduit by admitting air to break the suction, I could accomplish the same result by applying the valve 24 directly to the conduit I2 so that the fuel would be positively shut off, and the claim should be given a broad construction accordingly.

I have shown this structure in Figure 3 in which corresponding reference numerals indicate parts corresponding to those indicated by the same reference numerals in Figure 1, except that where a slight change in shape or location of a part has been made, the reference numeral is followed by the letter A. The operation of the device shown in Figure 3 is similar to that of the device shown in Figure 1, except that the valve 24A is applied directly to the conduit l2, and the position of the spring and vent ports are reversed in the cylinder I6.

It will be understood that the invention is susceptible of many modifications, and, accordingly, I do not wish to be limited in my protection, except as set forth in the accompanying claims.

I claim:

1. In a carburetor for internal combustion engines, means forming a mixing conduit, said mixing conduit having an air inlet and a mixture outlet, a throttle valve controlling said mixture outlet, a main fuel nozzle discharging into said mixing conduit between said air inlet and said throttle, a second fuel nozzle discharging into said mixing conduit at points both anterior and posterior to said throttle when it is in closed position, and suction operated means for restricting the discharge of fuel at said second discharge nozzle whenever the suction posterior to the throttle exceeds the normal idling suction.

2. In a carburetor, means forming a mixing conduit, said mixing conduit having an outlet, a throttle valve mounted in said outlet, a fuel discharging idle port in the wall of said mixing conduit adjacent `to said throttle when it is in closed position, a cylinder fbrmed in the wall of said mixing conduit adjacent to the outlet thereof, a spring pressed piston mounted in said cylinder, a conduit leading from a point in said cylinder to said mixing conduit at a point posterior to said throttle, a passageway leading to said idle port and a valve carried by said piston and controlling said passageway, said spring being of such strength in relation to the area of said piston as to prevent operation thereof except when the normal idling suction is exceeded.

3.- In a carburetor, walls forming a mixing conduit, said walls terminating in a flange at the outlet of said mixing conduit, a throttle valve in said mixing conduit anterior to said outlet, a main nozzle, an idle port in the wall of said conduit and adjacent to said throttle when it is in closed position, valve means for affecting the discharge of fuel from said idle port without disturbing the discharge from the main nozzle, a cylinder formed in the wall of said mixing conduit, a piston in said cylinder, said piston being connected with said valve, and a port connecting said cylinder with the mixing conduit at a point posterior to said throttle.

' 4. In a carburetor, walls forming a mixing conduit, a throttle valve in said conduit, an idle port in said conduit at a point adjacent the throttle valve when it is in closed position, valve meansv constructed and arranged to modify the discharge of 'fuel thru said idle port, a cylinder formed in a wall-of said mixing conduit at a point adjacent to said throttle, a piston in said cylinder, said piston being operatively connected to said valve, springmeans for forcing said piston toward one end of said cylinder and a suction connection between the other end of said cylinder and a point in said mixing conduit posterior to the throttle valve.

5. A device of the character described in claim 4 and in which said spring is of such strength as to prevent the operation of the piston by the normal idling suction.

anamorf 3 6. In a carburetor having a throttle controlled for modifying the discharge of fuel from said mixing conduit and a source of fuel supply, a idling nozzle, a suction controlled device conmain fuel nozzle receiving fuel from said source nected to said mixing conduit at a point posterior and discharging into said mixing conduit anto the throttle and means associated with said terior to the throttle, an idling nozzle also resuction controlled device for operating said valve, ceiving fuel from said source and discharging at the discharge of fuel from said main nozzle being a point in said mixing conduit adjacent the throt independent of and unaffected by said Valve. tle valve when it is in closed position, a. valve GEORGE R.. ERICSON. 

